基于IEC 61850的微网能量管理系统数据通信模型及其验证

将IEC 61850系列标准应用于微网能量管理系统,可以规范、统一微网能量管理系统中的通信标准,解决不同厂商制造的设备间的互操作问题。文中将微网通信体系分为三层,详细设计了各层的体系结构及对应的IEC 61850服务器和IEC 61850客户端。根据IEC 61850标准建模规范和实时数据在能量管理系统中的应用特点,提出了面向分布式电源整体系统或负荷单元系统来建立微网底层设备的信息模型,并以风力发电单元为例介绍了建模过程。针对所建立的数据模型设计了4个实验,从不同的角度对微网各层通信体系结构下的信息交互进行了实际测试。测试结果验证了所建立信息体系和微网IEC 61850模型的有效性,同时为数据交换模式的优化提供了基础,为微网的设备集成、运行分析及智能控制提供了有效的技术手段。     

基于统一潮流灵敏度的电-气-热综合能源系统安全控制策略

为提升对太阳能等可再生能源的利用能力,并解决边远地区或小型系统的稳定供电问题,独立光储直流微网的稳定运行控制受到了研究者的关注。针对光储直流微网各元件的底层控制方面,提出了光伏MPPT和CV模式的统一控制方法。为保证光储直流微网在不同光照和储能电量条件下的稳定运行,将光储直流微网的工作模式分为三种,分别对应于光伏和蓄电池的不同元件底层控制方式。对于微网的控制方式,考虑分散控制策略,并在此基础上提出了一种以蓄电池为中心、带单向通信的分布式控制策略,在不同策略下对微网工作模式的切换方式进行了设计。最后,仿真与实验结果表明所提的微网工作模式及其切换方式能够正常工作,所提出的分布式控制策略相比于分散控制策略改善了控制性能,保证了经济性,满足系统可靠性要求。     

交流配电系统中微网群管控一体化策略

微网群位于多节点配电网系统中,目前的研究大多只针对微网群的控制策略或能量调度问题,没有同时针对这两种问题进行的研究.因此,提出一种上层调度与下层控制联合优化的管控一体化策略.上层调度系统采用基于二阶锥优化的最优潮流算法对多节点系统进行能量调度,并与节点内微网群实时信息交互.下层微网群控制系统中提出一种改进的混合优化控制...     

Multi-agent approach to modeling and simulation of microgrid operation with vehicle-to-grid system

This study presents the modeling and simulation of a vehicle-to-grid (V2G) system within a microgrid considering the requirements of various components of the microgrid system such as distributed renewable energy resources (DERs), plug-in electric vehicles (PEVs) and non-PEV loads. The system modeling is carried out using an agent-based methodology where components of the microgrid are modeled as agents. The use of PEV car batteries collectively as a virtual power plant (VPP) enables PEVs to not only act as loads but as energy sources alongside DERs such as wind and solar power generation. The smart control and scheduling of the charging and discharging of the PEVs by the charging station can be used to achieve sustainable integration of a high number of PEVs in the microgrid power system. In addition to simulating a microgrid operation, results of this study show how agents’ behavior change based on factors such as penetration of renewable energy, penetration of PEVs, travel pattern of PEV drivers and price of energy generation.     

基于模糊最小二乘支持向量机的微电网群状态评估方法

针对微电网群能量管理与协调控制系统适应多微电网间多工况控制策略灵活调整的需要,提出了一种基于模糊最小二乘支持向量机(FLS-SVM)的低压微电网群运行状态实时评估模型。该模型基于传统电力系统运行状态描述方法,建立了微电网群及子微电网安全正常运行的边界条件,以电压偏移率、储能剩余容量及充放电时间、发用电功率等多维度特征向量对子微电网状态分类,应用FLS-SVM对子微电网的实时运行状态进行评估,最后判别出微电网群运行状态。实例计算分析表明,该模型可跟随系统采样周期实时评估,对离、并网条件下子微电网运行状态均能实现准确有效地分类,为微电网群快速判断网内状态并灵活调整控制策略提供依据。     

微网实时数据库系统研究

微网是一种新的分布式能源组织方式和结构。微网的结构特点和运行控制方式对微网能量管理系统(microgrid energy management system,MEMS)中实时数据库系统的实时性和可靠性提出了更高的要求。为此首先根据公共信息模型(common information model,CIM)扩展导则和微网的特点,扩展了微网CIM类的描述,并利用面向对象的实时数据库直接存储CIM的方法构建遵循标准的系统,以避开模型转换和数据映射,便于维护数据和提高实时数据库的访问效率。对实时数据库内部结构进行了研究设计和优化,提出一种双实时库的外部结构。最后给出了该实时数据库系统的工作流程并进行了性能测试,结果表明所设计的实时数据库完全适用于微网能量管理系统。     

信息系统对微电网能量调度经济性的影响量化方法

信息系统的失效将会影响微电网能量调度策略的运行经济性,为此提出量化信息系统对微电网能量调度策略经济性影响的分析方法,用于提升信息系统的可靠性。该方法通过研究微电网能量调度机理建立对应的信息系统模型,并结合物理系统拓扑模拟信息物理融合环境下能量调度策略的运行过程。以微电网交互成本和电动汽车用户成本为分析指标,基于模拟的运行过程,该方法能够计算微电网在考虑信息系统失效后的实际经济效益,并通过对模型参数、信息元件及拓扑结构的灵敏度分析有效识别和改善信息系统的薄弱环节。     

Power quality enhancement in autonomous microgrid operation using Particle Swarm Optimization

This paper presents an optimal power control strategy for an autonomous microgrid operation based on a real-time self-tuning method. The purpose of this work is to improve the quality of power supply of the microgrid where some Distributed Generation (DG) units are connected to the grid. Voltage and frequency regulation, and power sharing are the main performance parameters which are considered in this work, particularly during the transition from grid-connected to islanding operation mode and also during load change. In this work, two typical DG units are connected in parallel to configure the microgrid. The controller scheme is composed of an inner current control loop and an outer power control loop based on a synchronous reference frame and the conventional PI regulators. The power controller employs two typical strategies: active–reactive power (PQ) control strategy and voltage–frequency (Vf) control strategy. Particle Swarm Optimization (PSO) is an intelligent searching algorithm that is applied for real-time self-tuning of the power control parameters. The proposed strategy in this paper is that both DG units adopt the Vf control mode once the microgrid is islanded in order to regulate the microgrid voltage and frequency, whereas during the load change, only the second DG unit invokes the PQ control mode to ensure maximum power exportation. The results show that the proposed controller offers an excellent response to satisfy the power quality requirements and proves the validity of the proposed strategy.     

微电网能量管理系统中的公共信息模型扩展

能量管理系统应用程序接口标准IEC 61970的出现,促进了电力系统自动化向网络化、集成化发展。在IEC 61970的基础上进行公共信息模型扩展,提出了支路的概念,建立了光伏、风电、储能等不同支路模型;在此基础上建立高效低碳的微电网具体公共信息模型,构建完整的微电网信息模型,并将其应用到光储微电网能量管理系统的设计中,为进一步开发微电网能量管理系统高级应用程序提供了统一接口。     

基于储能荷电状态的主从控制微电网离网协调控制策略

双碳和新型电力系统建设目标下集成优化资源的微电网将是电网公司实现该目标的重要载体。微电网支持并网或离网运行,其离网运行可以提高供电可靠性,这是微电网的重要特性。离网运行的微电网需要合适的稳态控制策略,以保证微电网的长期稳定运行。目前一些依赖预测信息和采用模糊智能算法的能量管理方法在微电网的长期实际运行中会产生较大的稳态控制误差。为了更好地解决微电网离网运行时电力电量平衡定量的计算问题,提高微电网离网稳态控制精度,研究了基于储能电池荷电状态的主从控制微电网离网实时稳态协调控制策略,提出了微电网离网有功协调控制间歇电源调整、负荷调整、微电网停运等关键操作中储能荷电状态控制节点值的精确工程计算方法。针对实际微电网应用工程开展了协调控制策略的具体应用,仿真和实际运行证明了所提控制策略和计算方法的有效性。     

Control and protection of a microgrid connected to utility through back-to-back converters

This paper discusses the control and protection of a microgrid that is connected to utility through back-to-back converters. The back-to-back converter connection facilitates bidirectional power flow between the utility and the microgrid. These converters can operate in two different modes-one in which a fixed amount of power is drawn from the utility and the other in which the microgrid power shortfall is supplied by the utility. In the case of a fault in the utility or microgrid side, the protection system should act not only to clear the fault but also to block the back-to-back converters such that its dc bus voltage does not fall during fault. Furthermore, a converter internal mechanism prevents it from supplying high current during a fault and this complicates the operation of a protection system. To overcome this, an admittance based relay scheme is proposed, which has an inverse time characteristic based on measured admittance of the line. The proposed protection and control schemes are able to ensure reliable operation of the microgrid.     

Integration of a hybrid fuel cell-battery system to a distribution grid

In order to integrate a proton exchange membrane type (PEM) fuel cell system (FCS) combined with a battery bank to a distribution grid; this paper proposes a local controller based on fuzzy logic. The proposed system provides primary frequency control and local bus voltage support to the local grid. This opposes the passive distributed generation of the present that do not provide auxiliary services, such as back-up power, voltage support and reliability of supply as they operate under constant power factor equal to 1 at all times. During network disturbances, the distributed generations of the present are disconnected until normal operation is reestablished. When the distributed generation penetration is high this may lead to system instability. The microgrid concept is the effective solution for the control and quality improvement of grids with high level of DG penetration. So, the proposed system, also, can be an active controllable microsource of a microgrid in the future that cooperates with other microsources in order to cover the local load demands for active and reactive power either under grid-connected mode or under islanding operating mode. In cases where the distribution grid (working as microgrid) is forced to operate in islanded mode, the hybrid system provides the demanded active and reactive power. The FCS is connected to a weak distribution grid so that the system performance is studied under the worst conditions. The simulation results are obtained using MATLAB software under a severe step load change where the grid is still connected and under islanded operation. In both cases the system presents a good performance.     

Optimum battery energy storage system using PSO considering dynamic demand response for microgrids

This article proposes a novel optimum sizing of battery energy storage system (BESS) using particle swarm optimization (PSO) incorporating dynamic demand response (DR) to improve a fast, smooth and secure system stability and performance, avoiding a microgrid from instability and system collapse during an emergency situation. An optimum size of BESS integrating DR can play an important role in frequency control of the microgrid in order to rapidly improve the system stability, restore the power equilibrium and prevent system collapse in the microgrid. The optimum size of BESS is evaluated by PSO incorporating DR based on frequency control of the microgrid. The results show that the optimum size of BESS-based PSO with DR can improve a fast, smooth and safe system performance and dynamic stability compared with the optimum size of BESS-based simulated annealing (SA) with DR and the conventional size. Nevertheless, the proposed sizing methods also determined the impact of BESS specified costs between modern and conventional BESS technologies. The capital cost, operating and maintenance cost of BESS were then investigated and compared in terms of economical performance for microgrid operations.     

微网孤岛运行的分散自趋优控制策略

提出了一种适用于微网孤岛运行的分散自趋优控制策略,该策略无需微网中央控制器和通信系统即可实现系统的三次分层控制,包括分散一次控制、分散二次控制和分散三次控制。其中,一次控制沿用传统的线性下垂控制策略,保持了微网良好的线性动态特性;二次控制仅借助各台分布式发电机的输出端频率信息即可直接参与系统调频,使微网的频率能够维持在允许的范围内;三次控制采用考虑发电机成本的非线性下垂控制策略,使各台分布式发电机遵循等微增率准则,实现微网的优化运行。此外,通过设计不同时间常数的低通滤波器,使三次分层控制实现了动态解耦,使控制策略既能满足微网静态特性的要求,又具有良好的动态特性。最后,由仿真算例验证了所提控制策略的有效性。     

基于范德波尔振荡器和PQ控制的微电网并离网协调控制策略

针对微电网中采用传统多层嵌套的并离网下垂控制系统存在动态响应速度较慢、均流性能较差等问题,提出了一种基于范德波尔虚拟振荡器控制器（VOC）和PQ控制的微电网并离网协调控制方法。在微电网并网运行时,通过对离网VOC引入并网电流反馈,并对其谐振参数和电压倍率进行闭环调节,使VOC一直处于热备用状态,不仅使微电网中各发电单元拥有PQ控制的良好动态性能,还可实现并离网的平滑切换。在微电网转孤岛运行后,同样对VOC参数进行闭环调节,实现对微电网中公共耦合点（PCC）处负载电压的补偿以及对各发电单元更好的均流控制。给出VOC参数同步控制器与PCC处电压之间的关系,理论分析实现同步的机理。与基于传统下垂控制的并离网控制策略进行仿真对比,结果表明所提控制策略可以有效改善微电网在并网运行时的动态响应和孤岛运行时的均流性能。     

基于强化学习的多微电网分布式二次优化控制

针对微电网中分布式电源下垂一次控制产生的系统频率和电压静态偏差问题,提出了一种基于强化学习就地反馈方法的分布式二次优化控制,利用本地信息可兼顾频率恢复和电压调整的需求。首先,针对微电网经济性、频率及电压控制需求和各分布式电源综合性能(环境效益、经济效益、技术效益),定义了本地奖励,协调多微电网的频率恢复和电压调节。其次,针对电网实际运行情况,在满足供需平衡的同时,使用多智能体强化学习算法对全局奖励反馈优化修正,使各分布式电源协同出力渐近消除频率偏差,保证微电网的稳定运行。最后,通过实例验证了所提出控制的有效性和适应性。     

The China Light and Power Company energy management system

A modern energy management system (EMS) that has been in operation at the China Light and Power Company (CLP) in Hong Kong for over five years is described. The EMS is located in a building specifically designed for a system control center and also includes facilities for support staff. Although the EMS was designed to monitor and control the CLP transmission and generation network, the control center includes other auxiliary and support facilities, such as an operator training simulator, distribution control, maintenance workshops, communication facilities, power supplies and personnel offices. An introductory section of the paper explains the basis for the installation of the EMS. This is followed by discussions which explain the scope of the control center, the unique operational conditions addressed, unique control problems addressed, applications, and changeover experiences. The rapid growth of the service area and experience with this control center have led to an upgrading planned for completion in 1991. The justification and scope of this upgrading are presented. Operator training is a continuing process at the CLP control center. This activity has been incorporated into the overall configuration and into the plan for the EMS. Its execution is described     

考虑不确定性和含换电站的直流微电网优化研究

为了提高直流微电网的经济效益和缓解电动汽车行驶里程有限、充电时间长所带来的问题,提出了一种含分布式能源和电池交换站的直流微电网孤岛运行优化模型。建立了以直流微电网日运行成本、污染治理成本和电池交换站日运行成本及其约束为目标的经济调度模型,同时考虑了可再生能源如风力发电、光伏发电等存在输出功率不稳定的严重问题,利用鲁棒优化对其不确定性进行建模,利用CPLEX软件求解该混合整数规划问题。最后通过算例验证了所提出的优化模型可以降低含电池交换站的孤岛直流微电网的运行成本,提高风力和光伏的利用率。     

信息系统对微电网运行可靠性的影响分析

微电网是一种集成分布式电源、储能装置、能量转换装置、负荷、监控与保护装置等的小型发配用电系统,属于典型的信息物理系统。对微电网内各个单元的协调优化控制很大程度上依赖安全可靠的信息系统,信息系统的失效将很有可能影响微电网的安全稳定运行。文中提出了一种旨在量化信息系统元件故障和信道质量对微电网运行可靠性影响的分析方法,首先建立信息系统静态连接模型和动态传输模型,然后运用蒙特卡洛方法模拟微电网信息物理系统的运行过程,以电量不足期望和失负荷概率为指标,量化分析信息系统的不可靠对微电网运行可靠性的影响,并重点针对信息系统元件故障率和信道质量水平两方面的影响因素进行了灵敏度分析。算例结果验证了所提模型和方法的有效性。     

微电网并网运行的市场运营机制设计

在输配分开的电力市场环境下,为了实现微电网的智能化市场运作,需要结合微电网自身特点设计一套可行的市场运行机制。提出“发电驱动负荷”模式,在保证与主网电力市场相容的基础上,基于多代理系统的市场运营控制体系,计及可中断负荷和储能装置的灵活市场行为,融入需求侧响应机制,负荷用户可根据自身相对需求向微电网市场控制平台提交需求报价信息,构建微电网并网运行的合同市场和实时平衡市场,设计了竞价规则和模型,并针对几个关键问题进行了讨论。